/Engine/Plugins/Online/OnlineSubsystem/Source/Public/Interfaces/OnlineSessionInterface.h
Called when a user receives a session invitation. Allows the game code to decide on accepting the invite. The invite can be accepted by calling JoinSession()
typedef TMulticastDelegate_FourParams< void, const [FUniqueNetId](API\Runtime\CoreOnline\Online\FUniqueNetId) &, const [FUniqueNetId](API\Runtime\CoreOnline\Online\FUniqueNetId) &, const [FString](API\Runtime\Core\Containers\FString) &, const [FOnlineSessionSearchResult](API\Plugins\OnlineSubsystem\FOnlineSessionSearchResult) & > FOnSessionInviteReceived